Conventional thermodes are heated with power-line frequency power coupled to the thermodes by means of high current capacity power cables from large power transformers located remote from the thermodes. These power transformers are typically controlled by line voltage triacs. This conventional apparatus and method for powering thermodes, using long, heavy cables and large power transformers, is unsatisfactory for use in many automatic assembly machines where the parts placement heads must be capable of multiple functions and high speed movement.